Many indigenous languages in North America are almost extinct because of colonization. But in Latin America, many indigenous languages are still spoken widely, with Nahuatl still having >1.7 million speakers and Quechua with >10 million speakers according to official sources. Why is this the case?

One of the reasons why Nahuatl and Quechua are well preserved and widely spoken to this day (in contrast to some North-American indigenous languages) is because they were both the former languages of once powerful empires and used as a lingua franca. The languages were spread over a wide geographic area and were once spoken by tens of millions of people.

In comparison, no North-American indigenous language was spoken by this many millions of people and neither over such a large geographic area before colonization.

Nahuatl, originating from Mexico Valley, served as the lingua franca spoken of the Aztec Empire and Quechua served as the lingua franca spoken of the Inca Empire. The Aztec expanded to rule over most of central Mexico, while the Inca ruled over most of the Andes mountains and Pacific coast. Both of these Empires were in fact very diverse realms, and the Aztec and Inca ruled over many other ethnic groups and their languages became dominant and soon spread over a wide geographic area, and were regarded as prestige languages because they were the language of the ruling elite and used in commerce.

With regards to Aymara, they were ruled by the Inca, but they retained a high-level of autonomy, preserved their language, and Aymara functioned as a second official language in the Inca Empire. Other languages such as Mapuche, in modern-day Chile, were greatly influenced by Quechua.

When the Spanish conquered the Aztec and Inca, they in fact encouraged the use of Nahuatl and Quechua as a lingua franca because they desired a single language to facilitate communication with the indigenous people. It was simpler for the Spanish to master one native language and be able to communicate with the majority of the native population, as opposed to learning several. The Spanish administration in the 16th century supported the use of major native languages (Nahuatl and Quechua) as co-official with Spanish. This contributed greatly to the literary development of both languages, although this was in the form of Latinization and precolonial scripts were abandoned.

Spanish priests especially supported the use of Nahuatl in Mexico, and Quechua in Peru, for evangelizing the native population. This had the effect of further expanding the range of these languages, while at the expense of smaller native languages like Aymara for example and many others in Mexico. In the 16th century Spanish friar Domingo de Santo Tomás wrote the first Quechua grammar book, while friars Bernardino de Sahagún and Alonso de Molina wrote the first Nahuatl grammar and religious books.

Languages policies changed drastically over the centuries.

For example, in 1696 King Charles II made Spanish the official language and banned indigenous languages (later was lifted). And after the Túpac Amaru uprising in the 1780s, indigenous culture was suppressed and the Quechua language banned.

In the 1800s with the independence of Mexico, Peru, and many other Latin-American states, a policy of Hispanization was forced on the native population in the hopes it would better unite them in the new nation-state. Over the years Spanish became dominant in urban areas, and as the population urbanized over-time, this led to a decline in the number of native speakers. This remains the current issue that has led to the decline of Quechua and Nahuatl and Aymara, among others.

This was the language policy history of Spanish colonial America, and it is of course much different than in North America. Whereas the Spanish colonists lived among the native population and made an effort at learning their language, the British colonists in North America lived isolated away from the natives and the US pursued a policy of aggressive expansion and displacement of the Native-Americans into reservations. The US and Canada never made an indigenous language official, whereas in many Latin-American countries the indigenous languages are recognized on the official level and indigenous culture is part of the national identity.

I would certainly place great emphasis on the fact more Native people live in Central and South America, than in North America. The US and Canada only have 8-10 million combined, while Latin-America has 60 million.